[Gulp35]

the 71J go to warming the silicon die 10C over ambient.
Specific Heat (amount of energy required to raise 1g of substance 1C or K) of silicon is .71J/g*C so for a 10g piece of silicon to be rasied 10C ((.71J/g*c)*10g*10C)=71J.
there is my 71J

I was not describing the water temp in the enitre system but the temp of the water as it is exiting the block (i.e. warmed water that has not passed through the radiator to be cooled).

Yes the water temperature goes up if we are measuring the exit temperature
but No the water inlet temp will not change dramaticly if a large enough radiator is given (Heatecores are designed to handle a lot more than 100W of heat , I think i heard that 1 horsepower is equal to ~700W).